Continuous orbit panographic x-ray

ABSTRACT

X-ray apparatus for taking panoramic radiographs of structures, such as teeth, arranged in an arcuate line without shifting the subject. The X-ray source and film carrier are mounted on a common support which is adapted to revolve about the subject while the axis of revolution is driven in an arcuate path located within and substantially concentric with the arch of the structures&#39;&#39;curvilinear configuration.

United States Patent Faude et a]. 1 Jan. 18, 1972 4 TIN RBIT PANQGRAPHIC2,798,958 7/1957 Hudson et a] ..250/6l.5 [5 1 UOUS 0 3,045,118 7/1962Hellman et al. .....250l6l.5 3,536,913 10/1970 lrluchel ..250/6l.5 [72]Inventors: Jack Herman Fnude, Brooklyn; Henry Hellman, Sea Cliff, bothof NY. Primary Examiner-William F. Lindquist Attorney-Carl A. l-lechmer,Jr. and Stanley Bilker [73] Assignee: Pennwalt Corporation,Philadelphia, Pa. [22] Filed: Jan. 27, 1970 ABSTRACT [21] APPL 0 5 X-rayapparatus for taking panoramic radiographs of structures, such as teeth,arranged in an arcuate line without shifting the subject. The X-raysource and film carrier are mounted [52] US. Cl. ..250/6l.5, 250/50,250/65 R, on a common suppen which is adapted to revolve about the250/70 subject while the axis of revolution is driven in an arcuate path[51] Int. Cl. ..G01n 21/00, H01 1 37/00 located within and subsmmiauyconcentric with the arch of [58] Field of Search ..250l50, 52, 61.5, 65R, 70 the stmcmms'cuwflinear configuratiom [56] References Cited 8Claims, 10 Drawing Figures UNITED STATES PATENTS i 9 m V W 0 V I in m 1I I Smathers "250/ 5 PATENTEUJAN18|972 3.636.349

SHEET 1 BF 4 INVENTORS JA CK H. FAUDE HENRY HOLL MA N ATTORNEY PATENIEDmm 1972 3.636349 sum 2 or 4 INVE'N 70/?5 JA CK H. mun: HENRY HOLLMANPATENTEnJAmm I 3,636,349

sum 320E 4 INVENTORS JACK H. FAUDE HNRY HOLLMAN ATTORNEY FIG. 8 7/3 INVE N 70/?5.

.m CK H. FA u0 HENRY HOLLMAN A r TOR/VEY CONTINUOUS ORBIT PANOGRAPIIICX-RAY This invention relates to X-ray apparatus for taking panoramicradiographs of parts and structures which arranged within a subjectalong an arcuate line, for example, the teeth, the jaws, the skull. Moreparticularly, this invention relates to radiographic apparatus fortaking full mount X-rays by means of a film plate located outside themouth, all without shifting the patient during the exposure scanningprocess or without making abrupt position shifts of the apparatus itselfto accommodate for the complex arch of the teeth. I

In prior U.S. Pat. No. 2,684,446 to Paatero, there is shown aradiographic process in which the patient himself is rotated about animaginary axis passing axially through his body. This earlierconstruction not only encountered the distinct psychological problem ofmoving the patient himself or suspending him in awkward positions, italso caused'the projection of the exposure line to pass through adjacentoverlapping parts thereby causing distortionand shadows.

In U.S. Pat. No. 2,798,958 to Hudson et al., there is shown aradiographic apparatus in which the patient remains fixed while theX-ray source and film plate located outside the subjects body arerotated about the subject. The film plane is moved relative to themotion of the X-ray sourceand relative to the position of the toothbeing radiographed so that only the intended object tooth remains infocus during the scanning process while the teeth lying along anotherplane are blurred. However, the Hudson et al., system requires that theX-ray apparatus itself be shifted into two discrete positions whosecorresponding axes are the opposite side molars in order to accommodatefor the geometrically complex arch of the teeth. As a consequence,elaborate procedures are required to locate and displace the equipmentof the discrete axes in addition to the problem of superimposing theleft and right radiographs with respect to each other.

In prior U.S. Pat. No. 3,045,118 to Hollman et al., there is shown adental radiographic apparatus which includes a laterally movableplatform for holding the patient and shifting him from one side to theother in orderlto take successive X- ray scans of his left and rightside dentures.

The present inventionconcems a dental radiographic apparatus in whichthere is no shifting of the patient whatsoever and in which a smooth andcontinuous traverse of the dental arch is performed to effect exposurealong a line substantially normal to the curvilinear line of the teethfrom a single setup position.

It is an object of this invention to provide a dental X-ray apparatusfor taking a panographic exposure of the entire arch of the teeth in asingle continuous extra-oral pass without shifting the patient andwithout requiring multiposition setup.

Another object of this invention is to provide a panographic X-rayapparatus for taking a continuous radiograph .of stationary structuresarranged along an 'arcuate path within a body while always orienting theexposure axes substantially normal to the curvilinear line of thestructures.

Still another object of this invention is to provide apanographic dentalX-ray apparatus in which acontinuous radiograph is produced withoutbeing subject to interfering shadows of intermediate structures. 7

Yet another object of this invention is to provide a panographic dentalX-ray apparatus in which adjustment can be made for variations in thedental arch.

Yet still another object of this invention is to provide a dental X-rayapparatus for taking extra-oral panographic radiographs of teeth ofchildren or adults.

A still further object of this invention is to provide an extraoraldental panographic X-ray apparatus in which a continu-' ous radiographof the entire dental arch is obtained with a single pass withoutshifting the patient or without being subject to obscuring influences ofthe spinal column structure.

Other objects of this invention are to provide an improved device of thecharacter described which is easily and economically produced, which issturdy in construction and both highly efficient and effective inoperation.

With the above and related objects in view, this invention consists ofthe details of construction and combination of parts as will be morefully understood from the following detailed description when read inconjunction with the accompanying drawings in which:

FIG. 1 is a perspective view of a panoramic exposure dental X-rayapparatus embodying this invention.

FIG. 2 is an enlarged side elevational view of the X-ray source and filmcarrier yoke which is rotatable by a drive assembly embodied in thisinvention 'about an axis orbiting in a circular path.

FIG. 3 is a sectional view taken along lines 3-3 of FIG. 2.

FIG. 4 is a sectional view taken along lines 4-4 of FIG. 3.

FIG. 5 is a view taken along lines 5-5 of FIG. 2.

FIG. 6 is a sectional view taken along lines 6-6 of FIG. 2.

FIG. 7 is a fragmentary side view of a modified form of the driveassembly for orbiting the axis of revolution of the yoke about anelliptical axis.

FIG. 7A is a fragmentary'perspective view of the modified form of thedrive assemblyfor varying the arcuate configuration of the orbitingpath. I v

FIG. 8 is a schematic view showing the circular path transcribed by theX-ray source-film carrier with respect to the arch of the teethwhenactuated by the drive assembly of the FIG. 2embodiment.

FIG. 9 is a schematic view showing the elliptical path transcribed bythe X-ray source-film carrier when actuated by the modified driveassembly of FIG. 7. I

Referring now in greater .detail to the drawings in which similarreference characters refer tosimilar parts, the instant inventionincludes a frame, generally designated as A, a yoke B which supports anX-ray source C and a film carrier D in spaced disposition respect toeach other, and a drive assembly,

generally designated as E, for orbiting the yoke about a rotating axisand revolving the axis about a curvilinear line which transcribes aclosed loop path. In this manner, the X-ray source C and the filmcarrier D are caused to revolve orbitally about the head of a patientwho remains fixed in position while the centerline of the orbitcontinuously moves through an arcuate path approximating the arch of thepatients teeth.

Referring to FIGS. 1 and 2, the frame A is generally conventionalinconstruction and comprises a wheeled base 10 which carries electricalcontrols housed in a cabinet 12 and an upstanding column 14 on which issupported a vertically adjustable trolley or carriage 16. A horizontalboom l8 cantilevers outwardly from the vertically adjusting carriage l6and bridges over the patient who is seated in a chair 20 usually on astationary foundation with his head restrained in chinrest 21. Aplatform 22 at the end of the boom 18 supports the drive assembly Ewhile a pedestal 24 mounted as a shroud over the platform carries anelectric motor-gear reducer unit 26 which actuates the drive assembly E.The yoke B is suspended from an orbiting rotary shaft 28 depending fromthe drive assembly E.

Referring now to FIGS. 3 and 4, the drive assembly E comprises an upperrotatable casing portion 30 which carries an upstanding stem 32. Thestem 32 is directly connected to the shaft of the motor drive unit 26through coupling 34 so that the casing 30 rotates therewith. The lowerperiphery of the casing 30 includes an outwardly divergent flange 36which is secured by circumfcrentially spaced,,screws 38 to a circulardisk 40 which acts as a thrust race. The disk 40 is slidably supportedat its outer margin upon a ball bearing lower race 42 which is securedupon an internal shoulder 44 formed within a lower housing 46. A dustring 48 having peripheral threads complementary with internal threads inthe lower housing 46 is threaded therein and urges upper ball bearingrace 50 into slidable engagement with the upper margin of the disk 40.Affixed about an offcenter aperture in: the disk 40 and upwardlyprojecting therefrom is a sleeve bearing 52 which rotatably supports theyoke drive shaft 28. A cup 54 at the upper portion of the sleeve 52 hasa ball bearing 55 which rotatably carries and supports the upper part ofthe drive shaft 28 while the medial portion of the shaft 28 is rotatablyjoumaled by bushing 56. Affixed by setscrews 58 to an intermediateportion of the drive shaft 28 adjacently below the bushing 56 is a spurgear 60. The spur gear 60 acts as a planetary gear in that its teethintermesh with those of a stationary internal gear 62 which has acentrally disposed aperture. The internal gear 62 is secured to aretainer ring 64 which is affixed within the lower portion of thehousing 46. The housing 46 itself is secured to the platform 22 above anopening therein by a plurality of screws 66 extending through a flangedportion 47. Thus, rotation of the upper casing 30 when driven by themotor drive 26 causes the shaft 28 to revolve in a circular pathdictated by the path of travel of the eccentrically disposed sleeve 52.At the same time the planetary gear 60 because of its engagement withthe internal gear 62 is caused to rotate about its central axis.Accordingly the shaft rotates in a predetermined relation to its path ofrevolution corresponding to the ratio of the diameter of the spur gear60 to the diameter of the internal gear 62.

The yoke B includes a bracket 70 from which both the X- ray source C andthe film carrier D depend. A tubular member 72 is retained in thebracket and holds a mount 74 at its terminus for pivoting the X-ray tubeC about a horizontal axis 76 or about an axis normal thereto as definedby arm 78.

The film carrier D is supported on the bracket 70 diametrically oppositeto the X-ray source C and is best shown in FIGS. 2 and 5. A shroudportion 80 defines a support for the camera casing 82 and includes apulley 84 over which passes a cable 86 for actuating the film carriage88. The front wall 90 of the casing 82 is made of radiopaque material,such as lead, and includes a vertical slit 92 centrally disposedtherein. The rear of the casing 82 has a hinged door 94 for gainingaccess to the interior for loading and unloading the film cassette intothe carriage 88. The cassette carriage 88 is suspended from a rail 96 bysuitable rollers 98 to permit the film cassette itself to be carriedpast the exposure slit 92. The lower end of the cable 86 is attached at100 to the left-hand end of the carriage 88 after passing over a lowerpulley 102. A wire cord 104 from spring motor 106 biases the carriage 88to the left. The cable 86 drives the carriage 8 8 and its film cassettefrom left to right as shown in FIG. 2 at a predetermined speed past theslit 92 in accordance with the following pattern.

Referring now to FIGS. 2 and 6, the upper end of the cable 86 is affixedto a cam 110 after passing over idler pulleys 112 and 114. The cam 110is rotatably supported on bearing 116 carried about the drive shaft 28but is held stationary thereon by restraining arm 118. One end of therestraining arm 118 is affixed to the cam 110 while the other end has apin 120 slidably engaging longitudinal slot 122 in a pivot limitingguide 124 secured to the underside of boom 18. The slot 122 accommodatesfor the arcuate path of travel transcribed by the drive shaft 28 butrestricts the degree of pivotal motion of the cam 110 on the shaft.Accordingly, as the yoke B revolves about the patient's head, the cable86 winds upon the grooved periphery of the cam 110 so as to draw thecassette carriage 88 past the slit 92 and successively expose the film.

Referring now to FIG. 8, the patient is seated in the chair 20 with hishead restrained against movement by chin rest 21 while the X-ray sourceC and film carrier D are oriented along line I-I'. The position of theaxis of shaft 28 substantially registers with point I such that thefirst exposure through slit 92 will be of rear molar T1. The shaft 28 ofthe yoke B rotates about its own axis while revolving smoothly andcontinuously through the arc defined by circle III'IX'XVI'. At the sametime, the cassette carriage 88 moves the film successively past the slitto expose the respective teeth T1 through T16 inclusive to the beam ofX-rays. It is worthy to note at this stage that the exposure of teeth T8and T9 intermediate lines VIII- VIII and IXIX would require the X-raybeam to pass through the dense structure of the spinal column. Hence,the rate of travel of the drive shaft 28 may either be slowed down atthe arc position of teeth T8 and T9 by appropriate controls of the drivemotor unit 26 or the voltage to the X-ray tube stepped up, again bysuitable circuitry to provide a greater intensity of the X-ray beam.

As may be seen from FIG. 8, the exposure of the teeth T1 through T16takes place while the axis of the shaft 28 continuously revolvessubstantially through a semicircular are starting with point I' andterminating with XVI, the intermediate points representing zones ratherthan stops since the panoramic exposure occurs while the X-ray source Cand the carrier D are making their sweep.

It is to be observed that the semicircular path defined by the movementthrough the points I'-VlIl'-XVI' falls within the arch of the teeth, forexample an arc of 1%-1IICI'1 diameter to correspond with the complexarch of an average molar spacing of 2 inches. To accomplish such atraverse, the pitch diameter of'theplanetary gear 60 is Vii-inch andintermeshes with an internal gear 62 whose pitch diameter is 3 inches.As may be easily computed, such a ratio of pitch diameters producesslightly more than a full rotation .of the planetary spur gear 60 as ittraverses through a half-circle of the internal gear 62. Accordingly,the direction of cxpos ure line I-I with respect to tooth Tl as well asthe intermediate exposure lines through XVIXVI with respect to thecorresponding teeth are always in phase as shown by the respectivearrows; Note that the direction of the lines of exposureis approximatelynormal to the arch of the teeth without shifting the chair 20 in whichthe patient is seated, without shifting the position of the patient'shead, or without shifting the X-ray apparatus 'itself once it has beenset up.

In FIG. 9 there is shown an elliptical path of travel for the axis ofthe drive shaft 28 to correspond more closely with the arch of theteeth. In this manner, the lines of exposure I "-I through XVI-XVI" areoriented more perpendicular to the arch of the teeth thereby eliminatingshadows created by overlapping teeth where the exposure lines wouldangularly pass through two or more adjacent teeth. The means foraltering the path of travel is best shown in FIGS. 7 and 7A. Instead ofconnecting the yoke B directly to the drive shaft 28, the yoke iscoupled to an adjustable eccentric or crank assembly E1.

The crank assembly E1 includes a slotted block 130 which is affixed tothe drive shaft 28. Slidably supported in the slot of the block 130 is aslide member 132 which can be shifted by a screw 134. The screw 134 isthreadedly engaged through the slide member 132 and axially restrainedwithin the ends of the block 130 so that shaft 28A can be orientedeccentrically on either side of the axis of shaft 28 or in exactregistration therewith. It is preferable to orient the slide crank E1and its slot substantially parallel with the line of the tubehead C- andfilm carrier D. By such a construction, orienting the block 132 to theright of the center line of the shaft 28 will cause the shaft 28A totranscribe an elliptical path shown in solid lines whose major axisconforms with that shown in FIG. 9. Adjustment of the block 132 by screw134 to the position where the axis of the shaft 28A is to the left ofshaft 28 causes the major axis of the ellipse to be shifted as shown indotted lines in FIG. 9. A vernier scale on the block and slide 132denotes the degree of eccentricity whereby the path of revolution of theyoke B can be varied to suit the particular arch of the teeth beingradiographed, for example to correspond with the narrow arch of childrenor to that of a wide-jawed adult.

What is claimed is:

1. X-ray apparatus for producing panoramic radiographs of structuresarcuately disposed along a generally curvilinear arch comprising aframe, an X-ray source, a film carrier, means constituting a yokesupporting said X-ray source and said film carrier in spaced dispositionwith respect to each other along an exposure line passing through thearch of the arcuately disposed structures, and drive means in said framefor rotating said yoke about an axis in a predetermined rotary directionwhile at the same time continuously displacing said axis orbitally inthe opposite rotary direction along an arcuate path located within thearch of the arcuately disposed structures without shifting saidstructures, said drive means including a stationary gear, a planetarygear in intermeshing engagement with said stationary gear and means forrotating said planetary gear with respect to said stationary gear.

2. The apparatus of claim 1 including means for adjustably suspendingsaid yoke laterally with respect to said drive means wherein said drivemeans orbits the axis of rotation of said yoke about an elliptical axis.

3. The apparatus of claim 1 wherein said stationary gear comprises aninternal gear.

4. The apparatus of claim 3 including an eccentric coupled to a shaft ofsaid planetary gear.

5. The apparatus of claim 4 including means for continuously adjustingsaid eccentric with respect to the shaft of said planetary gear.

X-ray apparatus for producing panoramic radiographs of structuresarcuately disposed along a generally'curvilinear arch comprising aframe, an X-ray source, a film carrier, a yoke supporting said X-raysource and said film carrier in spaced disposition from each other,drive means suspending said yoke within said frame so that a linepassing between said X-ray source and said film carrier intersects theline of the curvilinear arch, said drive means including a motor, astationary internal gear, a planetary spur gear in intermeshingengagement with said internal gear and rotated by said motor, and asupport member coupling an intermediate portion of said yoke to saidspur gear so that the support member will follow a generally curvilinearpath described by the orbit of said planetary spur gear and at the sametime rotate about the axis thereof, the gear ratios and diameters beingso arranged that said spur gear will rotate substantially 360 about itsown axis while transcribing a semicircular path within said internalgear, and means to move film in said film carrier transverse to theexposure line in response to orbital movement of said yoke.

7. The X-ray apparatus of claim 6 including means to adjustably displacethe support member for said yoke eccentrically with respect to the axisof said spur gear whereby said curvilinear path may be varied to followan elliptical configuration.

8. The X-ray apparatus of claim 7 including means for adjustablyorienting the major and minor axes of the elliptical path about a polaraxis.

1. X-ray apparatus for producing panoramic radiographs of structuresarcuately disposed along a generally curvilinear arch comprising aframe, an X-ray source, a film carrier, means constituting a yokesupporting said X-ray source and said film carrier in spaced dispositionwith respect to each other along an exposure line passing through thearch of the arcuately disposed structures, and drive means in said framefor rotating said yoke about an axis in a predetermined rotary directionwhile at the same time continuously displacing said axis orbitally inthe opposite rotary direction along an arcuate path located within thearch of the arcuately disposed structures without shifting saidstructures, said drive means including a stationary gear, a planetarygear in intermeshing engagement with said stationary gear and means forrotating said planetary gear with respect to said stationary gear. 2.The apparatus of claim 1 including means for adjustably suspending saidyoke laterally with respect to said drive means wherein said drive meansorbits the axis of rotation of said yoke about an elliptical axis. 3.The apparatus of claim 1 wherein said stationary gear comprises aninternal gear.
 4. The apparatus of claim 3 including an eccentriccoupled to a shaft of said planetary gear.
 5. The apparatus of claim 4including means for continuously adjusting said eccentric with respectto the shaft of said planetary gear. X-ray apparatus for producingpanoramic radiographs of structures arcuately disposed along a generallycurvilinear arch comprising a frame, an X-ray source, a film carrier, ayoke supporting said X-ray source and said film carrier in spaceddisposition from each other, drive means suspending said yoke withinsaid frame so that a line passing between said X-ray source and saidfilm carrier intersects the line of the curvilinear arch, said drivemeans including a motor, a stationary internal gear, a planetary spurgear in intermeshing engagement with said internal gear and rotated bysaid motor, and a support member coupling an intermediate portion ofsaid yoke to said spur gear so that the support member will follow agenerally curvilinear path described by the orbit of said planetary spurgear and at the same time rotate about thE axis thereof, the gear ratiosand diameters being so arranged that said spur gear will rotatesubstantially 360* about its own axis while transcribing a semicircularpath within said internal gear, and means to move film in said filmcarrier transverse to the exposure line in response to orbital movementof said yoke.
 7. The X-ray apparatus of claim 6 including means toadjustably displace the support member for said yoke eccentrically withrespect to the axis of said spur gear whereby said curvilinear path maybe varied to follow an elliptical configuration.
 8. The X-ray apparatusof claim 7 including means for adjustably orienting the major and minoraxes of the elliptical path about a polar axis.